LHC Seminar

# Observation of charm mixing at LHCb

## by Angelo Di Canto (Ruprecht-Karls-Universitaet Heidelberg (DE))

Tuesday, 4 December 2012 from to (Europe/Zurich)
at CERN ( 500-1-001 - Main Auditorium )
 Description Meson-antimeson mixing has been observed in the K0−K0bar, B0−B0bar and B0s−B0sbar systems. Evidence of mixing in the charm system has been reported by three experiments using different D0 decay channels, but only the combination of these results provides confirmation of D0−D0bar mixing with more than 5σ significance. We report a measurement of charm mixing using the time-dependent ratio of D0 → K+π− to D0 → K−π+ decay rates in D∗+-tagged events reconstructed in 1.0 fb−1 of integrated luminosity recorded by the LHCb experiment in 2011. We measure the mixing parameters x'2 = (−0.9 ± 1.3) × 10−4, y' = (7.2 ± 2.4) × 10−3 and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates RD = (3.52 ± 0.15) × 10−3. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1σ and represents the first observation of D0−D0bar oscillations from a single measurement. Webcast Please note that this event will be available live via the Webcast Service. Material: Organised by M. Mangano, C. Lourenco, G. Unal......................... **Tea and Coffee will be served at 10h30**